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OVERVIEW
========

This package contains a kernel driver for accessing the SMM BIOS
of various Dell laptops. The SMM BIOS is used on many recent laptops
to implement APM functionalities and to access custom hardware,
for example the cooling fans and volume buttons of the I8000.

The kernel driver reports the following information about the hardware:

    * BIOS version

    * serial number

    * CPU temperature

    * fan status

    * fan rotation speed (only on some models)

    * ac power status


THE KERNEL DRIVER
=================

The i8k SMM driver is included in the core kernel distribution.
The driver source in this package is needed only if you want to compile
the module for an older kernel version or if you need a more recent version
than the one available in the Linux kernel.

The driver has been reported to work with the following hardware and BIOS:

    Inspiron 510m  (BIOS A06), with force=1
    Inspiron 1100  (BIOS A06), one fan, no buttons
    Inspiron 2650  (BIOS A05)
    Inspiron 3700  (BIOS A15), no fan speed
    Inspiron 3800  (BIOS A14), no fan speed
    Inspiron 4000  (BIOS A10), no fan speed
    Inspiron 4100
    Inspiron 4150
    Inspiron 5100  (BIOS A06), one fan, no buttons
    Inspiron 5150  (BIOS A24), one fan, no buttons, force=1
    Inspiron 6400  (UK model)
    Inspiron 8000  (BIOS A17)
    Inspiron 8100  (BIOS A04)
    Inspiron 8200  (BIOS A06)
    Inspiron 8600  (BIOS A08), with force=1
    Inspiron 8600C (BIOS A11), with force=1
    Inspiron 9200
    Inspiron 9400/E1705
    Latitude C400  (BIOS A01)
    Latitude C510  (BIOS A07)
    Latitude C600  (BIOS A17)
    Latitude C610
    Latitude C800  (BIOS A17)
    Latitude C810  (BIOS A12)
    Latitude C840  (BIOS A10)
    Latitude CPiA  (BIOS A14), no fan speed
    Latitude CPt C-Series (BIOS A14), no fan speed
    Latitude CPx J750GT (BIOS A13), no fan speed
    Latitude D600  (BIOS A05)
    Latitude D800  (BIOS A00)
    Latitude X200  (BIOS A07)
    Precision (exact models unknown)
    Studio 1555
    Vostro 1400
    XPS M140

but will probably work on any recent Dell laptop. Note that on some models
or BIOS versions the fan speed is not available. On some BIOS also the BIOS
version is not available from SMM but the driver is able to obtain it using
another method.

The driver seems *NOT WORKING* on the following models:

    Inspiron 2500 (BIOS A10)
    Inspiron 3200
    Inspiron 3500
    Inspiron 5000e (BIOS A06)
    Inspiron 5150 (BIOS A23)
    Inspiron 7000
    Inspiron 7500
    Latitude CPx H450GT
    Latitude LS H500ST
    Latitude L400

On loading the module checks for the presence of a known Dell laptop
and refuses to load if running on an unknown system. You can however
force loading of the driver, for testing it on unknown hardware,
by passing the "force=1" option to insmod:

    insmod i8k.o force=1

Note that force loading of the module on unknown hardware could crash your
system and will anyway 'taint' the kernel. The force option is provided
only for testing purposes or for loading on systems where the BIOS version
can't be read from the SMM BIOS.

The information provided by the kernel driver can be accessed by simply
reading the /proc/i8k file. For example:

    $ cat /proc/i8k
    1.0 A17 2J59L02 52 2 1 8040 6420 1 2

The fields read from /proc/i8k are:

    1.0 A17 2J59L02 52 2 1 8040 6420 1 2
    |   |   |       |  | | |    |    | |
    |   |   |       |  | | |    |    | +------- 10. buttons status
    |   |   |       |  | | |    |    +--------- 9.  ac status
    |   |   |       |  | | |    +-------------- 8.  right fan rpm
    |   |   |       |  | | +------------------- 7.  left fan rpm
    |   |   |       |  | +--------------------- 6.  right fan status
    |   |   |       |  +----------------------- 5.  left fan status
    |   |   |       +-------------------------- 4.  CPU temperature (Celsius)
    |   |   +---------------------------------- 3.  serial number
    |   +-------------------------------------- 2.  BIOS version
    +------------------------------------------ 1.  /proc/i8k format version

A negative value, for example -22, indicates that the BIOS doesn't return
the corresponding information. This is normal on some models/bioses.

For performance reasons the /proc/i8k doesn't report by default the ac status
since this SMM call takes a long time to execute and is not really needed.
If you want to see the ac status in /proc/i8k you must explictitly enable
this option by passing the "power_status=1" parameter to insmod. If ac status
is not available -1 is printed instead.

The driver provides also an ioctl interface which can be used to obtain the
same information and to control the fan status. The ioctl interface can be
accessed from C programs or from shell using the i8kctl utility. See the
source file i8kctl.c for more information on how to use the ioctl interface.

The driver accepts the following parameters:

    force=1

	force loading of the driver on unknown hardware.

    ignore_dmi=1
	Continue probing hardware even if DMI data does not match.

    restricted=1

	allow fan control only to processes with the CAP_SYS_ADMIN capability
	set or processes run as root. In this case normal users will be able
	to read temperature and fan status but not to control the fan.
	If your notebook is shared with other users and you don't trust them
	you may want to use this option.

    power_status=1

	report ac status in /proc/i8k. Default is 0.

    fan_mult

	Factor to multiply fan speed with. Defaults is 30. For some systems
	the default is overwritten with a system specific value, typically 1.
	This is curently the case for Dell Studio laptops as well as for Dell
	XPS M140.

You can specify the module parameters when loading the module or as kernel
option when booting the kernel if the driver is compiled statically.

To have the module loaded atomatically at boot you must manually add the
line "i8k" into the file /etc/modules or use the modconf utility, if
available in your distribution, and select the i8k module. For example:

    $ cat /etc/modules
    # /etc/modules: kernel modules to load at boot time.
    #
    # This file should contain the names of kernel modules that are
    # to be loaded at boot time, one per line.  Comments begin with
    # a #, and everything on the line after them are ignored.
    #
    apm
    i8k

Any module parameters must be specified in /etc/modules.conf, for example:

    $ grep i8k /etc/modules.conf
    options i8k restricted=1

If you are using modconf the file /etc/modules.conf is updated automatically
with the options specified in the user interface.


TROUBLESHOOTING
===============

If you have problems loading the kernel module or have succesfully tested
it on different hardware please let me know your results. Don't forget to
include the following information:

    laptop model
    BIOS version
    driver version
    kernel config file
    kernel messages while loading the driver
    output of "cat /proc/i8k"

Before reporting bugs be sure to be using the latest kernel module
and the latest BIOS available for your laptop. Old versions of the
driver may not work correctly and old BIOS versios may not support
all the SMM functions used by the driver.

If your system reports very high fan speeds (often 80,000 rpm or higher),
it likely needs a fan multiplier value of 1 instead of the default 30.
Please report that situation so the driver can be updated accordingly.


CREDITS
=======

Most of this README file has been copied from the i8kutils package.
The original driver was written by Massimo Dal Zotto. The interface
to the hwmon subsystem was added by Jean Delvare. Many other developers
have contributed various pieces of code over time.